U.S. patent number 8,823,241 [Application Number 13/144,642] was granted by the patent office on 2014-09-02 for segmented stator for an axial field device.
This patent grant is currently assigned to Boulder Wind Power, Inc.. The grantee listed for this patent is James David Duford, James D. Jore, Lincoln M. Jore, Matthew B. Jore, Michael Kvam, David Samsel. Invention is credited to James David Duford, James D. Jore, Lincoln M. Jore, Matthew B. Jore, Michael Kvam, David Samsel.
United States Patent |
8,823,241 |
Jore , et al. |
September 2, 2014 |
Segmented stator for an axial field device
Abstract
An axial rotary energy device including a segmented stator
assembly having a plurality of segments arranged in an annular
array. Each stator segment is constructed by stacking a plurality
of PCB power conductor layers and a plurality of PCB series layers.
Each layer having radial conductors extending from an inner via to
an outer via. The vias electrically connect selected radial
conductors of the series conductor layer and power conductor layer.
Each power conductor layer includes a pair of positive and negative
terminal vias for one phase of the electric current connected to
selected outer vias. A daughter PCB layer electrically connects two
adjacent segments together by having a first portion electrically
connected to a negative terminal via located in one segment and a
second portion electrically connected to a positive terminal via
located in an adjacent segment together with a current conductor
electrically connecting the two terminal vias together.
Inventors: |
Jore; Matthew B. (Ronan,
MT), Duford; James David (Polson, MT), Kvam; Michael
(Polson, MT), Jore; Lincoln M. (Ronan, MT), Samsel;
David (Missoula, MT), Jore; James D. (Polson, MT) |
Applicant: |
Name |
City |
State |
Country |
Type |
Jore; Matthew B.
Duford; James David
Kvam; Michael
Jore; Lincoln M.
Samsel; David
Jore; James D. |
Ronan
Polson
Polson
Ronan
Missoula
Polson |
MT
MT
MT
MT
MT
MT |
US
US
US
US
US
US |
|
|
Assignee: |
Boulder Wind Power, Inc.
(Louisville, CO)
|
Family
ID: |
42340054 |
Appl.
No.: |
13/144,642 |
Filed: |
January 15, 2010 |
PCT
Filed: |
January 15, 2010 |
PCT No.: |
PCT/US2010/000112 |
371(c)(1),(2),(4) Date: |
July 14, 2011 |
PCT
Pub. No.: |
WO2010/083054 |
PCT
Pub. Date: |
July 22, 2010 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20110273048 A1 |
Nov 10, 2011 |
|
US 20140049130 A9 |
Feb 20, 2014 |
|
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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61205435 |
Jan 16, 2009 |
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Current U.S.
Class: |
310/268; 310/180;
310/71; 310/156.37; 310/179; 310/68R |
Current CPC
Class: |
H02K
3/26 (20130101); H02K 21/24 (20130101); H02K
1/12 (20130101); H02K 3/47 (20130101); H02K
2211/03 (20130101); H02K 2203/03 (20130101) |
Current International
Class: |
H02K
1/22 (20060101); H02K 3/26 (20060101); H02K
21/24 (20060101); H02K 1/27 (20060101) |
Field of
Search: |
;310/68R,71,156.37,268,179,180 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1732011 |
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Dec 2006 |
|
EP |
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10-285894 |
|
Oct 1998 |
|
JP |
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WO 2010083054 |
|
Jul 2010 |
|
WO |
|
Other References
International Search Report and Written Opinion for International
Application No. PCT/US2010/000112, mailed Mar. 16, 2010. cited by
applicant .
Office Action for Chinese Application No. 201080004779.4, mailed
Feb. 6, 2013. cited by applicant.
|
Primary Examiner: Kim; John K
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a National Stage Entry under 35 U.S.C.
.sctn.371 of PCT/US2010/000112, filed Jan. 15, 2010, and entitled
"Segmented Stator for an Axial Field Device," which claims priority
to and the benefit of U.S. Provisional Patent Application No.
61/205,435, filed Jan. 16, 2009, and entitled "Segmented Stator for
an Axial Field Machine."
Claims
We claim:
1. An axial field rotary energy device having positive and negative
polarity, multi-phase electric current terminals comprising: a
rotor having a plurality of permanent magnet poles; and a segmented
stator assembly having a plurality of stator segments arranged in
an annular array with each stator segment having: a plurality of
printed circuit board power conductor layers having at least one
power conductor layer for each phase of the electric current, each
of said power conductor layers having a pattern of a plurality of
radial conductors running between an inner via and an outer via,
said inner vias being located at an inner diameter of said power
conductor layer and said outer vias being located at an outer
diameter of said power conductor layers; each power conductor layer
further having a pair of positive and negative terminal vias of one
phase of the electric current and located adjacent an outer edge of
each power conductor layer and further having a pair of terminal
conductors for electrically connecting the positive and negative
terminal vias to selected outer vias; a plurality of printed
circuit board series layers, at least one of which is associated
with each power conductor layer, and each one including a pattern
of a plurality of radial conductors running between an inner via
and an outer via, said inner vias being located at an inner
diameter of said series conductor layer and said outer vias being
located at an outer diameter of said connecting series conductor
layer; each series conductor layer further having a plurality of
outer conductors for electrically connecting selected outer vias
together and a plurality of inner conductors for electrically
connecting selected inner vias together; the inner and outer vias
of the power conductor layer and the series conductor layer
arranged for electrically connecting selected ones of the radial
conductors of the series conductor layer to selected ones of the
radial conductors of the power conductor layer; a daughter printed
circuit board for electrically connecting two adjacent segments
together; each daughter printed circuit board having a first
portion electrically connected to a negative terminal via located
in one segment and a second portion electrically connected to the
positive terminal via located in an adjacent segment together with
a current conductor electrically connected between the said
negative terminal via and the said positive terminal via; and the
segmented stator assembly further including a pair of phase
conductors for electrically connecting the positive and negative
current terminal of one phase of the electric current to selected
ones of the positive and negative terminal vias of the segmented
stator assembly.
2. The axial field rotary device according to claim 1 wherein each
power conductor layer includes a plurality of inner conductors for
electrically connecting selected inner vias together.
3. The axial field rotary energy device according to claim 1
wherein each printed circuit board power layer has a planer
configuration and each circuit board series conductor layer has a
planer configuration and each stator segment is formed by stacking
the power conductor layers and the connecting conductor layers one
upon the other with a substrate layer in between each layer.
4. The axial field rotary energy device according to claim 1
wherein the stator assembly has a central bore there through in a
direction perpendicular to the planer configuration of the layers
and further including a rotatable driveshaft extending through the
central bore and further including a first rotor fixedly secured to
the driveshaft on one side of the stator and a second rotor fixedly
secured to the driveshaft on the opposite side of the stator
assembly.
5. The axial field rotary energy device according to claim 4
wherein the permanent magnet poles of the first rotor are
positioned with respect to the permanent magnet poles of the second
rotor so that flux lines pass through the stator assembly in a
direction perpendicular to the planer configuration of the power
conductor layers.
6. The axial field rotary energy device according to claim 1
wherein each power conductor layer and each series conductor layer
is divided into sectors with each sector associated with a positive
or negative polarity of each phase of the electric current and with
radial conductors running through each sector.
7. The axial field rotary energy device according to claim 1
configured for at least a 3-phase electric current.
Description
FIELD OF THE INVENTION
The present invention relates to an improved stator for an axial
field rotary energy device operating as a motor or a generator as
described in U.S. Pat. No. 7,109,625 to Jore et al.
BACKGROUND OF THE INVENTION
The size of machines that may be produced with a one-piece printed
circuit board (PCB) stator is limited by the capability of the
processing equipment found in a PCB manufacturing facility. High
volume facilities have a maximum size PCB panel that can be
processed on automated equipment. Certain lower volume facilities
routinely process larger PCB panel sizes than the high volume
manufacturers but there is a higher cost due to more labor and
higher material costs. In order to cost effectively produce large
axial field rotary machines that incorporate a PCB stator, a
segmented PCB stator is shown and described. The segments allow a
much larger diameter machine than is possible with single piece PCB
stator designs. Further, the segments may be produced in high
volume manufacturing facilities that provide the best cost.
SUMMARY OF INVENTION
The present invention provides an axial rotary energy device which
is arranged in a multi-phase electric current configuration. The
device includes a rotor having a plurality of permanent magnet
poles secured thereto and further includes a segmented stator
assembly having a plurality of segments arranged in an annular
array. Each stator segment is constructed by stacking a plurality
of printed circuit board power conductor layers together with a
plurality of much larger diameter machine than is possible with
single piece PCB stator designs. Further, the segments may be
produced in high volume manufacturing facilities that provide the
best cost.
SUMMARY OF INVENTION
The present invention provides an axial rotary energy device which
is arranged in a multi-phase electric current configuration. The
device includes a rotor having a plurality of permanent magnet
poles secured thereto and further includes a segmented stator
assembly having a plurality of segments arranged in an annular
array. Each stator segment is constructed by stacking a plurality
of printed circuit board power conductor layers together with a
plurality of printed circuit board series layers. Each stator
segment having at least one working power conductor layer for each
phase of the electric current and at least one series conductor
layer associated with one power conductor layer. Each power
conductor layer and series conductor layer having radial conductors
extending from an inner diameter via to an outer diameter via. The
vias are provided for electrically connecting selected ones of the
radial conductors of the series conductor layer to selected ones of
the radial conductors of the power conductor layer. Each power
conductor layer includes a pair of positive and negative terminal
vias for one phase of the electric current connected to selected
outer vias of the power conductor layer. A daughter printed circuit
board is used for electrically connecting two adjacent segments
together. Each daughter printed circuit board having a first
portion electrically connected to a negative terminal via located
in one segment and a second portion electrically connected to a
positive terminal via located in an adjacent segment. A current
conductor is provided on the daughter printed circuit board for
electrically connecting the negative terminal via and the positive
terminal via together.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be clearly understood and readily
carried into effect, a preferred embodiment of the invention will
now be described, by way of example only, with reference to the
accompanying drawings wherein:
FIG. 1 is an exploded assembly view with parts broken away of an
axial field device utilizing the present invention;
FIG. 2 is a cross-sectional view taken along the line 2-2 in FIG. 1
showing a first embodiment of the present invention;
FIG. 3 is a schematic view showing the electrical circuit for one
phase of the axial field device through selected stator segments
and daughter printed circuit boards;
FIG. 4 is a detail view of one segment of a power layer of a stator
board for phase A according to the first embodiment of the present
invention;
FIG. 5 is a detail view of one segment of a series layer of a
stator board for phase A according to the first embodiment of the
present invention;
FIG. 6 is a detail view of one segment of a power layer of a stator
board for phase B according to the first embodiment of the present
invention;
FIG. 7 is a detail view of one segment of a series layer of a
stator board for phase B according to the first embodiment of the
present invention;
FIG. 8 is a detail view of one segment of a power layer of a stator
board for phase C according to the first embodiment of the present
invention;
FIG. 9 is a detail view of one segment of a series layer of a
stator board for phase C according to the first embodiment of the
present invention;
FIG. 10 is a diagram showing one arrangement of the stacking of
power layers and series layers for phases A, B and C;
FIG. 11 is a diagram showing another arrangement of the staking of
power layers and series layers for phases A, B and C;
FIG. 12 is a detail view of one segment of a power layer of a
stator board according to a second embodiment of the present
invention;
FIG. 13 is a detail view of one segment of a power layer of a
stator board according to a third embodiment of the present
invention;
FIG. 14 is a plan view of a stator board showing the arrangement of
stator segments and daughter printed circuit boards according to
the first embodiment of the present invention;
FIG. 15 shows a daughter printed circuit board for the A phase;
FIG. 16 shows a daughter printed circuit board for the B phase;
FIG. 17 shows a daughter printed circuit board for the C phase;
FIG. 18 shows a daughter printed circuit board for the A, B, and C
phases electrically isolated;
FIG. 19 is a cross sectional view taken along the line 2-2 in FIG.
1 showing a fourth embodiment of the present invention; and
FIG. 20 is a perspective sectional view taken along the line 20-20
in FIG. 14.
DESCRIPTION OF A PREFERRED EMBODIMENT
An axial gap device 10 according to the present invention is shown
in FIG. 1 with a housing 12A having a number of terminal covers 14,
a pair of bearings 16, a drive shaft 18, a pair of rotors 20A and
20B each having an annular array of permanent magnets 22 that
alternate polarity around the array, another housing 12B, and a
segmented stator assembly 24. The segmented stator assembly 24 is
comprised of a pair of clamp rings 26A and 26B, a number of
fasteners such as bolts 28, a plurality of terminal lugs 30, and a
plurality of stator segments 32. The stator segments 32 are
comprised of multiple layer printed circuit boards that are shaped
to fit together to form an annular array of stator segments 32. The
multiple layers of conductive material in each stator segment 32
provide a number of turns for each electrical phase of the axial
gap device 10.
FIG. 2 illustrates how the clamp rings 26A and 26B and bolts 28
fasten onto either side of the inward edge of the stator segments
32. The outer edge of the stator segments 32 are held in place by
the clamping force of the housings 12A and 12B. The clamp rings 26A
and 26B and the housings 12A and 12B suspend the stator assembly 24
in the air gap between the permanent magnets 22 mounted on the
rotors 20A and 20B. As shown in FIG. 1, each stator segment 32 has
a plurality of terminal lugs 30. The terminal lugs 30 are made of
an electrically conductive material such as copper. The number of
lugs on each segment depends upon the number of electrical phases
in the machine. There is a positive and a negative terminal lug 30
for each phase. The illustrated device has three electrical phases
and so each stator segment 32 has six terminal lugs 30. FIG. 2
shows how each terminal lug 30 passes through a lug opening 34 in
the housing 12A to electrically connect the stator segment 32 to a
daughter printed circuit board 36. An insulating material may be
placed around the lug 30 where it passes through the lug opening 34
to prevent the lug 30 from making electrical contact with the
housing 12A. The terminal lugs 30 are attached to the stator
segments 32 and to the daughter printed circuit boards 36 by
soldering or by fastening with some other means, such as a threaded
nut over a threaded portion of a terminal lug 30. The multiple
layer daughter printed circuit boards 36 electrically connect each
phase in one stator segment 32 to each corresponding phase in an
adjoining stator segment 32.
FIG. 3 diagrammatically shows the electrical circuit for one phase
of the axial gap device 10 through selected stator segments 32 and
daughter printed circuit boards 36. An electrical current enters a
stator segment 32 through a positive terminal lug 30 for the
particular phase. The current flows through a first working turn 38
(a working turn is the torque producing portion of the circuit
within the magnetic gap of the axial field device 10), then into an
inner turn 40, then into a second working turn 42, then into an
outer end turn 44, and then into third working turn 46, and so on
until the electrical current has passed through all of the turns
for the particular phase in the stator segment 32. The first and
third working turns 38 and 46 are associated with one magnetic pole
and so the axial field device 10 shown is said to have two turns.
The electrical circuit of the diagram in FIG. 3 is shown with two
working turns however the number of working turns may be any number
depending upon the performance requirement of the axial field
device 10 and limited only by the physical space available for
working turns in the stator segment 32. Also illustrated in FIG. 3
is the relationship between the number of stator segments 32 in the
axial field device 10 to the number of magnet poles of magnets 22.
In the preferred embodiment, there will be two magnet poles for
every stator segment 32.
Continuing in FIG. 3, electrical current flows from the last
working turn into the negative terminal lug 30 and the into the
daughter printed circuit board 36 which conducts the electrical
current from the negative terminal lug 30 of the first stator
segment 32 to the positive terminal lug 30 of a second stator
segment 32. The electrical current then flows through all of the
turns for the particular phase in the second stator segment 32 and
then out through the negative terminal lug 30 of the second stator
segment to a second daughter printed circuit board 36. The
electrical current is conducted through the entire segment array in
the same manner.
FIG. 4 shows a pattern etched into one layer of conductive material
in one of the stator power segments 32A. The pattern has a variety
of conductive paths that relate to three electrical phases of the
axial field device 10. The pattern has A+, B+, C+, A-, B-, and C-
terminal lugs 30. Each of the terminal lugs 30 terminate in a
terminal pad 48. Each of the terminal pads 48 have a plurality of
terminal via 50 electrically connected to a respective terminal pad
48. A terminal conductor 52 electrically connects a terminal pad 48
to an outer via pad 54 having a plurality of outer vias 56. The
pattern shown in FIG. 4 is called a power layer for electrical
phase A since it is on this layer that the electrical connection is
made to the stator segment 32 for phase A. The terminal conductors
52 of the power layer are continuous with terminal pads A+ and A-.
Terminal pads 48 for B+, C+, B-, and C- are in contact with the
corresponding terminal lugs 30 but the pads are not connected to
terminal conductors 52 on this layer.
In FIG. 4, arrows show the direction of an electrical current to
illustrate the relationships of the conductors of the power layer
for phase A. The arrows are for reference only since the axial
field device operates as a brushless DC or synchronous AC motor or
generator. The current is shown to begin at the terminal pad 48 A+
and flow through the terminal conductor 52 to the outer via pad 54.
The outer via pad 54 is continuous with a first working conductor
38 on the power layer for phase A. The first working conductor 38
connects the electrical current to the inner via pad 58. As shown
in FIG. 4, the first working conductor 38 is substantially within
the flux of the permanent magnets 22. Electrical current flowing
through the first working conductor 38 will create the Lorenz force
that acts between the flowing current and the magnetic flux. The
outer via pad 54 has a number of outer vias 56 which are plated
through holes that electrically connect the outer via pad 54 on the
power layer for phase A to the corresponding outer via pads 54 on
all of the other conductive layers of the stator segment 32. The
inner via pad 58 also has a number of inner vias 60 that
electrically connect the inner via pad 58 on the phase A power
layer to the corresponding inner via pads 58 on all of the other
conductive layers of the stator segment 32.
As seen in FIGS. 4 through 9, the outer via pad 54 is continuous
with the first working conductor 38 on each of the conductive
layers. Therefore, the outer vias 56 and the inner vias 60 connect
all of the working conductors together so that the electrical
current flowing through the first working conductor 38 on the power
layer for phase A is in parallel with the corresponding working
conductors 38 on all of the layers of the stator segment. This is
the same for all of the working conductors for all of the phases of
the stator segment.
Continuing in FIG. 4, the electrical current flows from the inner
via pad 58 to the first inner end turn 40. From the first inner end
turn 40, the electrical current flows to an inner via pad 58 which
is connected to a second working conductor 42. The second working
conductor 42 carries the electrical current to an outer via pad 54.
The circuit appears to end at the outer via pad 54 but as
previously described, the inner and outer vias 60 and 56 connect
all of the second working conductors 42 on all of the layers of
conductive material in parallel. The next pattern to be described
shows how the circuit for phase A is continued.
FIG. 5 shows a pattern etched into another conductive layer of the
stator series segment 32B. The pattern shown in FIG. 5 is called a
series layer for electrical phase A since it contains the outer end
turns that electrically connect the working turns for phase A in
series. From the outer via pad 54 at the end of the second working
conductor 42, the electrical current flows into the first outer end
turn 44. The electrical current then flows to an outer via pad 54
with outer vias 56 and then to a third working conductor 62. From
the third working conductor 62, the electrical current flows into
an inner via pad 58 with inner vias 60. The third working
conductors 62 on all layers of conductive material of the stator
segment are electrically connected in parallel by the outer vias 56
and the inner vias 60. The electrical current continues from the
inner via pad 58 to a second inner end turn 64 and then to an inner
via pad 58 and then to a fourth working conductor 66. The
electrical current continues on through the working conductors,
outer via pads, outer end turns, inner via pads and inner end turns
as shown in FIG. 5 until reaching a tenth working conductor 68.
From the tenth working conductor 68, the electrical current flows
to an outer via pad 54 with outer vias 56. The circuit appears to
end at the outer via pad 54 but as previously described, the inner
and outer vias 60 and 56 connect all of the tenth working
conductors 68 on all of the layers of conductive material in
parallel. Referring again to FIG. 4, the electrical current moves
from the outer via pad 54 associated with the tenth working
conductor to a terminal conductor 52 and then to an A- terminal pad
48.
The patterns and electrical current flow is similar for the power
and series layers for phase B and phase C. FIG. 6 shows a pattern
etched into another layer of conductive material of the stator
power segment 32A that is a power layer for phase B. FIG. 7 shows a
pattern on another layer that is a stator series segment 32B for
phase B. FIG. 8 shows a pattern on a stator power segment 32A for
phase C. And FIG. 9 shows a pattern on a stator series segment
32B.
The multiple layer stator segments 32 of the annular array
comprising the entire stator are constructed by stacking the
individual stator power segments 32A and stator series segments 32B
for the A, B and C phases one on top the other with a substitute
dielectric layer 33 provided between each layer. The stacking order
of the stator power segments 32A and the stator series segments 32B
for phases A, B and C is selectable. There may be duplicates of
each layer type in the stator segment. There may be a greater
number of series layers than power layers in the stator segment.
The order of the layers is preferably selected to provide an even
distribution of electrical current throughout different layers of
the stator segment and particularly so that there is an even
distribution of electrical current through the axial length of the
inner and outer vias. The main benefit of the even distribution of
the electrical current is to optimize the thermal dissipation of
the stator segment 32. The durability of each stator segment 32 is
enhanced by reducing the thermal stress that can cause delamination
of the layers and cracking in the walls of the vias.
As a non-limiting example, a stator segment with eighteen layers
might have two power layers for phase A, four series layers for
phase A, two power layers for phase B, four series layers for phase
B, two power layers for phase C, and four series layers for phase
C. FIG. 10 shows one possible stacking arrangement of the layers
that provides an even distribution of the electrical current. FIG.
11 shows another possible stacking arrangement of the layers that
provides an even distribution of the electrical current and added
isolation of the phases for medium and high voltages.
FIG. 12 shows another embodiment of the stator segment 32. In this
embodiment, a pattern etched into a conductive layer of a stator
power segment 32A' includes the terminal conductors 52 for phases
A, B, and C. In this embodiment, the power layers for phases A, B,
and C as described above would be identical. The main benefit of
this embodiment is that there are more terminal conductors 52 in
parallel for each phase. However, the inner end turns that were
present on the power layers of 32A shown in FIGS. 4, 6, and 8 are
absent in this embodiment. With this stator power segment 32A', it
is necessary to use the three stator series segments 32B for the
phases A, B and C as shown in FIGS. 5, 7 and 9.
FIG. 13 illustrates another embodiment of the stator segment where
the inner end turns are present on a stator power segment 32A''
that contains terminal conductors 52 for phases A, B, and C. This
pattern would then be a power layer for phase A and the power
layers in this embodiment therefore are not identical. The power
layer for phase B would contain the inner end turns for phase B and
the power layer for phase C would contain the inner end turns for
phase C. With this stator segment 32A'' it is again necessary to
use the three stator series segments 32B for the phases A, B and C
as shown in FIGS. 5, 7 and 9.
FIG. 14 illustrates the arrangement of stator segments 32 and
daughter printed circuit boards 36 in one embodiment of a stator
assembly. The stator assembly has phase conductor wires 70 for
phases A, B, and C; an inner clamp ring 26A; bolts 28; and a
plurality of daughter printed circuit boards 36 attached to an
array of stator segments 32. The stator assembly 24 includes six
terminal lugs 30 which are connected to the six phase conductor
wires 70 as shown. The phase conductor wires 70 may be arranged as
shown or may be configured for a wye or delta connection with the
stator assembly 24 as is well known in the art.
The daughter printed circuit boards 36 are used to electrically
connect adjacent stator segments 32 together. As shown in FIG. 20,
the daughter boards 36 are arranged so that three terminal lugs 30
(A-, B- and C-) of a daughter printed circuit board 36 are
positioned over the corresponding terminal lugs 30 of one stator
segment 32 and three terminal lugs 30 (A+, B+ and C+) of the same
daughter printed circuit board 36 are positioned over the
corresponding terminal lugs 30 of the adjacent stator segment
32.
FIGS. 15 through 17 show the electrical current path on each of the
layers of conductive material in the daughter printed circuit
boards 36. FIG. 15 shows a pattern etched into a daughter printed
circuit board 36 with terminal vias 50 for A- and A+ having an
electrical current path between them. The terminal vias 50 for B-,
C-, B+, and C+ are isolated from the terminal vias 50 for A- and
A+. The terminal lugs 30 have terminal pads 48 with vias 50 that
electrically connect the terminal pads 48 to the corresponding
terminal pads 48 on all of the other layers of conductive material
of the daughter printed circuit boards 36. In FIG. 15, the
electrical current for phase A flows from the A- terminal pad 48
through the daughter printed circuit board 36 to the A+ terminal
pad 48. In FIG. 16, the electrical current for phase B flows from
the B- terminal pad 48 through the daughter printed circuit board
36 to a B+ terminal pad 48. In FIG. 17, the electrical current for
phase C flows from C- terminal pad 48 through the daughter printed
circuit board 36 to a C+ terminal pad 48. FIG. 18 shows daughter
printed circuit board 36 which has all of the terminal pads 48 for
the A-, B-, C-, A+, B+, and C+ isolated from one another. In a
preferred embodiment, the daughter printed circuit boards 36 shown
in FIGS. 15-17 are stacked one upon the other with a dielectric
substrate layer in between them. The daughter printed circuit board
36 shown in FIG. 18 is preferably placed on the first and the last
layer of the daughter printed circuit board stack in order to
electrically isolate the phases on the exterior surfaces the
daughter printed circuit boards 36.
FIG. 19 shows another embodiment of the invention which has a
stator assembly 24 with two arrays of stator segments 32. The
stator segments are electrically connected in parallel by the
terminal lugs 30. An outer spacer 74 and an inner spacer 76 keep
the stator segments apart to allow for electrical isolation and
thermal dissipation. Also shown in FIG. 19 is an arrangement of two
stacks of daughter printed circuit boards 36 mounted in parallel
across each set of terminal lugs 30. As should be understood by
this example, there can by more than two arrays of stator segments
32 within the stator assembly 24. Also it should be understood that
there may by more than two stacks of daughter printed circuit
boards 36 mounted in parallel across each set of terminal lugs 30.
The benefit of having arrays of stator segments 32 and stacks of
daughter printed circuit boards 36 mounted in parallel is to reduce
the electrical resistance of the circuit.
While the fundamental novel features of the invention have been
shown and described, it should be understood that various
substitutions, modifications, and variations may be made by those
skilled in the arts, without departing from the spirit or scope of
the invention. Accordingly, all such modifications or variations
are included in the scope of the invention as defined by the
following claims:
* * * * *